초록 ▼

The compression method utilizes a combination of both lossy and lossless compression to achieve significant compression while retaining very high subjective quality of the reconstructed or decompressed signal. Methods and apparatus for compression and decompression of digital audio data are provided

The compression method utilizes a combination of both lossy and lossless compression to achieve significant compression while retaining very high subjective quality of the reconstructed or decompressed signal. Methods and apparatus for compression and decompression of digital audio data are provided. In one preferred embodiment, the compression method or apparatus has a bit rate control feedback loop particularly well suited to matching the output bit rate of the data compressor to the bandwidth capacity of a communication channel. Embodiments trade-off various error sources in order to keep perceptible distortion levels to a minimum for a fixed bit rate. Preferred embodiments also utilize a unique combination of run length and Huffman encoding methods in order to take advantage of both local and global statistics.

대표청구항 ▼

[ What is claimed and desired to be secured by United States Letters Patent is:] [1.] A method for compressing digitally sampled audio data into an average bit rate of compressed audio data, comprising the steps of:a) performing a discrete wavelet transform on the digitally sampled audio data to obt

[ What is claimed and desired to be secured by United States Letters Patent is:] [1.] A method for compressing digitally sampled audio data into an average bit rate of compressed audio data, comprising the steps of:a) performing a discrete wavelet transform on the digitally sampled audio data to obtain resultant wavelet coefficients;b) eliminating according to a predetermined criteria a calculated fractional percentage of wavelet coefficients to achieve the average bit rate;c) quantizing the wavelet coefficients using a selected quantization level;d) entropy encoding the quantized coefficients to obtain the compressed audio data; ande) feeding the number of bits used to represent the entropy encoded coefficients back into the calculation of the fractional percentage of wavelet coefficients which must be eliminated to achieve the average bit rate.